1. Field of the Invention
The present invention relates to a vehicle rear left and right side warning apparatus, a vehicle rear left and right side warning method, and a three-dimensional (3D) object detecting device. In particular, the present invention relates to an apparatus, a method, and a device which photograph rear left and right sides of a vehicle by using cameras and which issue a warning upon detecting a 3D object, such as another vehicle or a pedestrian, and also to a 3D-object detecting device for use in the apparatus and the method.
2. Description of the Related Art
Recent years have seen active development of systems for enhancing safe driving of vehicles. As one of the developed technologies, there is a system in which a 3D object (such as another vehicle or pedestrian) that is present in the vicinity of a vehicle in question is detected and is reported to the driver. For example, with respect to images at the rear left and right sides of a vehicle in question which are captured by side cameras, one known system detects a 3D object having a predetermined shape by using pattern recognition technology and issues a warning when the detected 3D object comes within a predetermined distance of the vehicle, and another known system issues a warning when another vehicle traveling parallel to a vehicle in question is detected outside the range of the driver's view.
However, when a 3D object in the vicinity of the vehicle is detected with simple pattern recognition, there are cases in which an object other than other vehicles and pedestrians to be regarded as warning targets is detected and a false warning is issued. For example, since planted trees 101 in a median have elongated shapes, as illustrated in FIG. 7, in some cases they are recognized as two-wheeled vehicles or people, thus causing a false warning to be issued. There are also cases in which, as illustrated in FIG. 8, another vehicle 102 traveling in an opposite lane or a vehicle 103 parked in a lane in the same direction as that of a vehicle in question is recognized as a vehicle traveling in a lane in the same direction, thus causing a false warning to be issued.
Some systems aimed at increasing the accuracy of warnings have been proposed (e.g., see Japanese Unexamined Patent Application Publication No. 2008-34981 and Japanese Unexamined Patent Application Publication No. 2010-181928). The system disclosed in Japanese Unexamined Patent Application Publication No. 2008-34981 is intended to improve the accuracy of recognizing objects in images. The system is adapted to accurately identify a candidate area in which an object (a pedestrian) that is a determination target is highly likely to be present, by identifying, in an input image, an area other than road-surface-marking areas as a candidate area for pedestrian recognition.
In the system disclosed in Japanese Unexamined Patent Application Publication No. 2010-181928, the position of a sidewalk boundary is detected in addition to a moving object (a pedestrian) that is present in the vicinity of a vehicle. The system is further adapted to evaluate a degree of risk of collision of the vehicle with the moving object, considering its surrounding situation on the basis of position information of the moving object and the position of the sidewalk boundary, and to issue a warning on the basis of the degree of risk.
However, the systems disclosed in Japanese Unexamined Patent Application Publication No. 2008-34981 and Japanese Unexamined Patent Application Publication No. 2010-181928 are both technologies for increasing the accuracy of recognizing pedestrians to reduce false warnings. Hence, these systems do not overcome the problem that another vehicle traveling in an opposite lane or a vehicle parked in a lane in the same direction as that of a vehicle in question, as illustrated in FIG. 8, is recognized as a vehicle traveling in a lane in the same direction, thus causing a false warning to be issued. The systems disclosed in Japanese Unexamined Patent Application Publication No. 2008-34981 and Japanese Unexamined Patent Application Publication No. 2010-181928 are both intended to increase the recognition accuracy by identifying an area in which a pedestrian is highly likely to be present. However, even when such an area is identified, the problem still exists that, when an elongated 3D object exists in that area, as illustrated in FIG. 7, the object is recognized as a two-wheeled vehicle or a pedestrian, causing a false warning to be issued.